from django.shortcuts import render,get_object_or_404
# render 渲染函数
from django.http import HttpResponse,HttpResponseRedirect
from .models import Question,Choice
from django.template import loader
from django.http import Http404
from django.urls import reverse
from django.views import generic
# 通信请求
# Create your views here.
# 函数视图
# def index(request):
#     # 获取筛选后的问题列表
#     latest_question_list = Question.objects.order_by('-pub_date')[:5]
#     output = ', '.join([q.question_text for q in latest_question_list])
#     # 自动在templates文件中寻找
#     template = loader.get_template('polls/index.html')
#     # context传入模板的参数，将模板变量(左)和 python对象 的映射
#     context={'latest_question_list':latest_question_list,}
#     return HttpResponse(template.render(context,request))

# def detail(request,question_id):
#     try:
#         question=Question.objects.get(pk=question_id)
#     except Question.DoesNotExist:
#         raise Http404("Question does not exist")
#     return render(request,'polls/detail.html',{'question':question})
    

# def results(request,question_id):
#     question = get_object_or_404(Question, pk=question_id)
#     return render(request, 'polls/results.html', {'question': question})
class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        """Return the last five published questions."""
        return Question.objects.order_by('-pub_date')[:5]
    
    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['earliest_question_list'] = Question.objects.order_by('-pub_date')[:5]  # 获取最早发布的五个问题
        return context

class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'


class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'

def vote(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        # Redisplay the question voting form.
        return render(request, 'polls/detail.html', {
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
        # Always return an HttpResponseRedirect after successfully dealing
        # with POST data. This prevents data from being posted twice if a
        # user hits the Back button.
        # 重定向，args表示参数dd
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))